Blood circulates continuously in the blood vessel system. It performs very important functions in the body: respiratory, transport, protective and regulatory, ensuring the constancy of the internal environment of our body.

Blood is one of the connective tissues, which consists of a liquid intercellular substance with a complex composition. It includes plasma and cells suspended in it or the so-called blood cells: leukocytes, erythrocytes and platelets. It is known that in 1 mm 3 of blood there are leukocytes from 5 to 8 thousand, erythrocytes - from 4.5 to 5 million, and platelets - from 200 to 400 thousand.

The amount of blood in the body of a healthy person is approximately 4.5 to 5 liters. 55-60% by volume is occupied by plasma, and 40-45% of the total volume remains for the shaped elements. Plasma is a translucent yellowish liquid, which contains water (90%), organic and mineral substances, vitamins, amino acids, hormones, metabolic products.

The structure of leukocytes

Erythrocytes

Erythrocytes and leukocytes are present in the blood. Their structure and function are different from each other. An erythrocyte is a cell that has the shape of a biconcave disc. It does not contain a nucleus, and most of the cytoplasm is occupied by a protein called hemoglobin. It consists of an iron atom and a protein part, and has a complex structure. Hemoglobin carries oxygen in the body.

Erythrocytes appear in the bone marrow from erythroblast cells. Most red blood cells are biconcave, and the rest may vary. For example, they can be spherical, oval, bitten, cup-shaped, etc. It is known that the shape of these cells can be disrupted due to various diseases. Each red blood cell is in the blood for 90 to 120 days, and then dies. Hemolysis is a phenomenon of destruction of red blood cells, which occurs mainly in the spleen, as well as in the liver and blood vessels.

Platelets

The structure of leukocytes and platelets is also different. Platelets do not have a nucleus; they are small oval or round cells. If these cells are active, outgrowths form on them, they resemble a star. Platelets appear in the bone marrow from the megakaryoblast. They "work" only from 8 to 11 days, then die in the liver, spleen or lungs.

Very important. They are able to maintain the integrity of the vascular wall, restore it in case of damage. The platelets form a blood clot and thereby stop the bleeding.

In modern diagnostics, the calculation of the number of leukocytes is considered one of the most important laboratory tests. After all, the rapidity of the increase in the concentration of white blood cells indicates how strong the immune system and the body's ability to protect itself from damage. This can be a common cut of a finger in a household, an infection, a fungus and a virus. How leukocyte cells help to cope with foreign agents, we will talk in the article.

What are white blood cells?

Leukocytes - white blood cells, from a medical point of view - heterogeneous groups of cells, different in appearance and functional purpose. They form a reliable line of defense of the body against adverse external influences, bacteria, microbes, infections, fungi and other foreign agents. They are distinguished by the presence of a kernel and the absence of their own color.

White cell structure

The structure and function of cells are different, but they all have the ability to emigrate through the capillary walls and move through the bloodstream to absorb and destroy foreign particles. With inflammation and diseases of an infectious or fungal nature, leukocytes increase in size, absorbing abnormal cells. And over time, they self-destruct. But as a result, harmful microorganisms are released that caused the inflammatory process. In this case, there is swelling, an increase in body temperature and redness of the site of localization of inflammation.

Terms! Chemotaxis of leukocytes is their migration to the inflammatory focus from the bloodstream.

The particles that trigger the inflammatory response attract the right amount of white blood cells to fight off foreign bodies. And in the process of the struggle, they are destroyed. Pus is a collection of dead white blood cells.

Where are leukocytes formed?

In the process of ensuring a protective function, leukocytes produce protective antibodies that will manifest themselves in inflammation. But most of them will die. Place of formation of white cells: bone marrow, spleen, lymph nodes and tonsils.

Terms! Leukopoiesis is the process of the appearance of leukocyte cells. This occurs most often in the bone marrow.

How long do leukocyte cells live?

The life span of leukocytes is 12 days.

Leukocytes in the blood and their rate

To determine the level of leukocytes, it is necessary to conduct a complete blood count. Units of measurement of the concentration of leukocyte cells - 10 * 9 / l. If the analyzes show a volume of 4-10 * 9 / l, you should rejoice. For a healthy adult, this is a normative value. For children, the level of leukocytes is different and is 5.5-10 * 9 / l. A general blood test will determine the ratio of different types of leukocyte fractions.

Deviations from the normative limit of leukocyte cells may be laboratory error. Therefore, leukocytosis or leukocytopenia is not diagnosed on a single blood test. In this case, a referral is given for another analysis to confirm the result. And only then the question of the course of treatment of pathology is considered.

It is important to take a responsible attitude to your health and ask your doctor what the tests show. Approaching the critical border of the level of leukocytes is an indicator that you need to change your lifestyle and diet. Without active action, when people do not draw the right conclusions, disease comes.

Table of norms of leukocytes in the blood

How is the number of leukocytes in plasma measured?

Leukocyte cells are measured during the blood test using a special optical device - the Goryaev camera. Counting is considered automatic and provides a high level of accuracy (with minimal error).

Goryaev's camera determines the number of leukocytes in the blood

The optical device is a glass of special thickness in the form of a rectangle. It has a microscopic mesh on it.

Leukocytes are counted as follows:

Acetic acid tinted with methylene blue is poured into a glass test tube. This is a reagent into which you need to drop a little blood with a pipette for analysis. After that, everything mixes well.
Wipe the glass and camera with gauze. Next, the glass is rubbed against the chamber until rings of different colors begin to form. The chamber is completely filled with plasma. You need to wait 60 seconds until the cells stop moving. The calculation is carried out according to a special formula.

Leukocyte functions

First of all, mention should be made of the protective function. It involves the formation of the immune system in a specific and non-specific embodiment. The mechanism of operation of this defense involves phagocytosis.

Terms! Phagocytosis is the process of capturing hostile agents by blood cells or their successful destruction.

The transport function of leukocytes in an adult ensures the adsorption of amino acids, enzymes and other substances, their delivery to their destination (to the desired organ through the bloodstream).
The hemostatic function in human blood is of particular importance for clotting.
The definition of sanitary function is the breakdown of tissues and cells that have died in the process of injury, infection and injury.

Leukocytes and their functions

The synthetic function will provide the required number of leukocytes in the peripheral blood for the synthesis of biologically active components: heparin or histamine.

If we consider the properties of leukocytes and their functional purpose in more detail, it is worth mentioning that they have specific characteristics and capabilities due to their variety.

Leukocyte composition

To understand what leukocytes are, you need to consider their varieties.

Neutrophil cells

Neutrophils are a common type of white blood cell that makes up 50-70 percent of the total. Leukocytes of this group are produced and moved in the bone marrow and belong to phagocytes. Molecules with segmented nuclei are called mature (segmented), and with an elongated nucleus - stab (immature). The production of the third type of young cells occurs in the smallest volume. Whereas there are most mature leukocytes. By determining the ratio of the volume of mature and immature leukocytes, you can find out how intense the bleeding process is. This means that significant blood loss prevents the cells from maturing. And the concentration of young forms will exceed their congeners.

Lymphocytes

Lymphocytic cells have a specific ability not only to distinguish congeners from a foreign agent, but also “remember” every microbe, fungus and infection that they have ever encountered. It is the lymphocytes that are the first to strive to the focus of inflammation to eliminate the "uninvited guests". They build a defense line, launching a whole chain of immune reactions to localize inflammatory tissues.

Important! Lymphocytic cells in the blood are the central link of the body's immune system, which instantly moves to the inflammatory focus.

Eosinophils

Eosinophilic blood cells are inferior in number to neutrophilic ones. But in the functional direction, they are similar. Their main task is to move in the direction of the lesion focus. They easily pass through vessels and can absorb small foreign agents.

Functionally, monocytic cells are capable of absorbing larger particles. These are tissues affected by the inflammatory process, microorganisms and dead leukocytes, which self-destructed in the process of fighting foreign agents. Monocytes do not die, but are engaged in the preparation and cleaning of tissues for regeneration and final recovery after an infectious, fungal or viral lesion.

Monocytes

Basophils

This is the smallest group of leukocyte cells in terms of mass, which in relation to its congeners is one percent of the total. These are the cells that, as first aid, appear where you need to instantly respond to intoxication or damage from harmful toxic substances or vapors. A striking example of such a defeat is the bite of a poisonous snake or spider.

Due to the fact that monocytes are rich in serotonin, histamine, prostaglandin and other mediators of the inflammatory and allergic process, cells block poisons and their further spread in the body.

What does an increase in the concentration of leukocyte particles in the blood mean?

An increase in the number of leukocytes is called leukocytosis. The physiological form of this condition is observed even in a healthy person. And this is not a sign of pathology. This happens after a long-term exposure to direct sunlight, due to stress and negative emotions, heavy exercise. In females, high white blood cells are observed during pregnancy and the menstrual cycle.

When the concentration of leukocyte cells exceeds the norm by several times, you need to sound the alarm. This is a dangerous signal indicating the course of a pathological process. After all, the body is trying to defend itself against a foreign agent by producing more defenders - leukocytes.

After the diagnosis is made, the attending physician has to solve one more problem - to find the root cause of the condition. After all, it is not leukocytosis that is treated, but what caused it. As soon as the cause of the pathology is eliminated, after a couple of days the level of leukocyte cells in the blood will return to normal on its own.

Blood is the most important tissue of the human body that performs important functions: transport, metabolic, and protective. The last, protective function of the blood is provided by special cells - leukocytes. Depending on the structure and special purpose, they are divided into separate types.

Classification of leukocytes:

Granulocytic:

neutrophils;
basophils;
eosinophils.

Agranulocytic:

monocytes;
lymphocytes.

Types of leukocytes

It is customary to divide white blood cells primarily by structure. Some contain granules inside, therefore they are called granulocytes, in others such formations are absent - agranulocytes.

In turn, granulocytes are classified according to their ability to perceive certain dyes for neutrophils, basophils, eosinophils. Cells that do not have granules in their cytoplasm are monocytes and lymphocytes.

Types of leukocytes

Neutrophils

One of the most numerous populations of leukocytes in adults. It got its name from its ability to stain with dyes with neutral pH. As a result, the granules inside the cytoplasm acquire a color ranging from purple to brown. What are these granules? These are a kind of reservoirs for biologically active substances, the action of which is aimed at destroying genetically foreign objects, maintaining and regulating the vital activity of the immune cell itself.

Bone marrow neutrophils are differentiated from stem cells. In the process of maturation, they undergo structural changes. This mainly concerns the change in the size of the nucleus, it acquires a characteristic segmentation, respectively, decreasing in size. This process takes place in six stages - from juvenile to adult forms: myeloblast, promyelocyte, myelocyte, metamyelocyte, stab, and then segmented neutrophil.

Observing neutrophils of various maturities under a microscope, one can see that the nucleus of the myelocyte is round, and that of the metamyelocyte is oval. The stab has an elongated nucleus, and the segmented one has 3-5 segments with constrictions.

Neutrophils

Neutrophils live and mature in the bone marrow for about 4-5 days, and then enter the vascular bed, where they stay for about 8 hours. Circulating in the blood plasma, they scan the tissues of the body and, upon detecting "problem areas", penetrate there and fight the infection. Depending on the intensity of the inflammatory process, their lifespan in tissues ranges from several hours to three days. After that, the neutrophils, valiantly fulfilling their functions, are destroyed in the spleen and liver. In general, neutrophils live for about two weeks.

So, how does a neutrophil work when it detects a pathogenic agent or a cell with altered genetic material? The cytoplasm of white blood cells is plastic, capable of stretching in any direction. Approaching a virus or bacteria, the neutrophil captures it and absorbs it. The same granules are connected inside, from which enzymes are released, aimed at destroying a foreign object. In addition, in parallel, the neutrophil is able to transmit information to other cells, triggering the process of an immune response.

Basophils

The structure is very similar to neutrophils, but only the granules of these cells are sensitive to basic dyes with a more alkaline pH. After staining, the granularity of the basophils acquires a characteristic dark purple, almost black color.

Basophils also mature in the bone marrow and go through the same developmental stages from myeloblast to mature cells. Then they enter the bloodstream, circulate there for about two days and penetrate into the tissues.

These cells are responsible for generating an inflammatory response, attracting immune cells to tissues and transmitting information between them. The role of basophils in the development of anaphylactic-type reactions is also interesting. Biologically active substances released from granules attract eosinophils, the amount of which determines the intensity of allergic manifestations.

Basophils

Eosinophils

In order to find these cells in a blood smear, a dye with an acidic pH is required. In practice, eosin is most often used, in fact, from here these cells got their name. After staining, they turn bright orange. A characteristic distinguishing feature is the size of the granules - they are much larger in size than that of neutrophils or basophils.

The development of eosinophils is not fundamentally different from that of other granulocytes; it also occurs in the bone marrow. However, after entering the vascular bed, eosinophils rush in bulk to the mucous membranes. They are capable of absorbing disease-causing agents, like neutrophils, only they work in mucous membranes, for example, the digestive tract, trachea and bronchi.

Along with this, eosinophils play a huge role in the development of allergic reactions. A large number of biologically active substances released during the rupture of eosinophil granules cause symptoms characteristic of people suffering from atopic dermatitis, bronchial asthma, urticaria, and allergic rhinitis.

Eosinophil

Monocytes

These agranulocytic cells can be of various shapes: with a rod-shaped, oval or segmented nucleus.

They are formed in the bone marrow from a monoblast and almost immediately enter the bloodstream, where they circulate for 2-4 days. The main function of monocytes is to regulate the immune response by releasing various regulatory substances from the granules that increase or decrease inflammation. In addition, monocytes contribute to tissue regeneration, skin healing, and the restoration of nerve fibers.

Macrophages

These are all the same monocytes, but migrated into the tissue from the vascular bed. When stained, the mature cell acquires a bluish color. There are a large number of vacuoles in its cytoplasm, therefore macrophages are also called "foam cells". They live in tissues for several months. The peculiarity is that some of them can be "wandering" and circulate through different tissues, and some are "stationary". Such cells in certain tissues have different names, for example, macrophages of the liver - Kupffer's cells, of the brain - microglia cells, and those that provide bone renewal - osteoclasts. Provide phagocytosis of pathogenic objects.

Lymphocytes

The cells are round in shape with a relatively large nucleus. Lymphocytes are formed in the bone marrow from a precursor cell - lymphoblast, they go through several stages. Moreover, primary differentiation occurs in the bone marrow, and secondary differentiation occurs in the spleen, lymph nodes, Peyer's patches and, mainly, in the thymus.

Lymphocytes that have undergone additional ripening in the thymus are called T-lymphocytes, and in other immune organs - B-lymphocytes. Such double preparation is extremely necessary, because these are the most important immunocompetent cells that provide the body's defense. They circulate in the blood for three months and, if necessary, penetrate the tissues, performing their functions.

T-lymphocytes provide nonspecific immunity, fighting against all objects carrying foreign genes: bacteria, viruses, tumor cells. In addition, T cells are subdivided into varieties, depending on the function they perform.

T-killers are cells of the first line of defense, they provide ultra-fast reactions of cellular immunity, destroy virus-infected or tumor-changing cells.
T-helpers are cells that help transmit information about foreign material, cooperating with the work of other immune cells. As a result of this influence, the response develops more intensively and faster.
T-suppressors are cells whose duties include the regulation of the work of T-killers and T-helpers. They prevent an overly active immune response to various antigens. If the function of T-suppressors is impaired and reduced, then autoimmune diseases and infertility develop.

B-lymphocytes create specific immunity, having the ability to form antibodies against certain agents. Moreover, T-lymphocytes are active mostly against viruses, and B-lymphocytes - against bacteria.

B cells support the formation of memory immune cells. Having met once with a foreign agent, the body forms immunity and resistance to certain bacteria and viruses. Vaccination works the same way. Only in vaccine preparations are bacteria and viruses in a killed or weakened state, unlike those that can be found in ordinary habitats. Some memory cells are especially stable and provide lifelong immunity, others die over time, therefore, to prevent especially dangerous infections, revaccination is carried out.

Lymphocytes

The number of leukocytes in normal and pathological conditions

Of course, only a doctor can correctly decipher a clinical blood test. After all, the number of leukocytes even in a completely healthy person is not constant, this can be influenced by food intake, physical activity, pregnancy. For an in-depth study of the immune status, a consultation with an immunologist and an immunogram is required, which displays in detail the number of the main types of leukocytes, populations and subpopulations of immune cells.

table normal leukocyte counts in different groups of people

Changes in the leukocyte formula are specific. It is difficult to understand complex laboratory parameters on their own, only doctors can do it. Focusing on the analyzes and the clinical picture of the disease, they can make a diagnosis on time and correctly. Therefore, do not engage in self-diagnosis and self-medication, seek qualified medical help and be healthy!

Examining blood under a microscope, one can find rather large cells with nuclei; they look transparent. These are white blood cells or leukocytes.

LEUKOCYTES (from the Greek leukos - white and from the Greek kytos - receptacle, here - a cell), colorless. human and animal blood cells. All types of L. (lymphocytes, monocytes, basophils, eosinophils, and neutrophils) have a nucleus and are capable of active amoeboid movement. In the body, bacteria and dead cells are absorbed, and antibodies are produced. 1 mm3 of the blood of a healthy person contains 4-9 thousand L.

Their number varies depending on food intake and physical activity. Leukocytes are divided into granulocytes (containing grains, granules) and agranulocytes (non-granular leukocytes).

Leukocytosis (leukocytosis, leukos - white, cytos - cell) is a pathological reaction of the body, manifested by an increase in the content of leukocytes in the blood over 9x109 / l.

Leukopenia (leukopenia, leukos - white, penia - poverty) is a pathological reaction of the body, manifested by a decrease in the content of leukocytes in the blood below 4 × 109 / l.

GRANULOCYTES, leukocytes of vertebrates and humans, containing grains (granules) in the cytoplasm. Formed in the bone marrow. According to the ability of the grains to be painted special. paints are divided into basophils, neutrophils, eosinophils. Protect the body from bacteria and toxins.

AGRANULOCYTES (non-granular leukocytes), leukocytes of women and humans, which do not contain grains (granules) in the cytoplasm. A. - immunological cells. and the phagocytic system; are divided into lymphocytes and monocytes.

Granular leukocytes are divided into eosinophils (whose grains are stained with acid dyes), basophils (whose grains are stained with basic dyes), and neutrophils (stained with both dyes).

EOSINOPHILS, one of the types of leukocytes. They are stained with acidic dyes, including eosin, red. Participate in allergies. body reactions.

BASOPHILES, cells containing structures in the cytoplasm, stained with basic (alkaline) dyes, the type of granular blood leukocytes, and also defined. cells of the anterior pituitary gland.

NEUTROPHILES, (from Lat. Neuter - neither one nor the other and ... phyl) (microphages), one of the types of leukocytes. N. are capable of phagocytosis of small foreign particles, including bacteria, and can dissolve (lyse) dead tissue.

Agranulocytes are divided into lymphocytes (cells with a round dark nucleus) and monocytes (with an irregularly shaped nucleus).

LYMPHOCYTES (from lymph and ... cit), one of the forms of non-granular leukocytes. Allocate 2 main. class L. V-L. come from the bursa (in birds) or bone marrow; from them plasmatic are formed. cells that produce antibodies. T-L. come from the thymus. L. are involved in the development and maintenance of immunity, and also, probably, supply nutrition. in other cells.

MONOCYTES (from mono ... and ... cit), one of the types of leukocytes. Capable of phagocytosis; excreting from the blood into the tissue when it becomes inflamed. reactions, function like macrophages.

FORK GLAND (thymus, thymus), center. an organ of the immune system of vertebrates. In most mammals, it is located in the region of the anterior mediastinum. Well developed at a young age. Participates in the formation of immunity (produces T-lymphocytes), in the regulation of growth and general development of the body.

Leukocytes are complex in structure. The cytoplasm of leukocytes in healthy people is usually pink, the granularity in some cells is red, in others it is purple, in others it is dark blue, and in some there is no color at all. German scientist Paul Erlig processed blood smears with a special paint and divided leukocytes into granular and non-granular. His research was deepened and developed by D.L. Romanovsky. He found out what paths blood cells pass in their development. The solution he compiled for staining blood helped to reveal many of its secrets. This discovery entered science as the famous principle of "Romanovsky's coloring". The German scientist Arthur Pappengein and the Russian scientist A. N. Kryukov created a coherent theory of hematopoiesis.

By the amount of leukocytes in the blood, a person's illness is judged. Leukocytes can move independently, pass through tissue gaps and intercellular spaces. The most important function of leukocytes is protective. They fight microbes, absorb and digest them (phagocytosis); discovered by II Mechnikov in 1883. Through persistent long-term research, he proved the existence of phagocytosis.

MACROPHAGES (from macro ... and ... phage) (polyblasts), cells of mesenchymal origin in women and humans, capable of actively capturing and digesting bacteria, cell debris and other particles foreign or toxic to the body (see Phagocytosis). M. include monocytes, histiocytes, etc.

MICROPHAGES, the same as neutrophils,

Leukocyte formula is the percentage of various forms of leukocytes in the blood (in a stained smear). Changes in the leukocyte count may be typical for a particular disease.

2. Blood plasma, the concept of serum. Plasma proteins

Blood plasma is the liquid part of blood. Blood plasma contains corpuscles (erythrocytes, leukocytes, platelets). Changes in the composition of blood plasma are of diagnostic value in various diseases (rheumatism, diabetes mellitus, etc.). Medicines are prepared from blood plasma (albumin, fibrinogen, gammaglobulin, etc.). Human blood plasma contains about 100 different proteins. By mobility during electrophoresis (see below), they can be roughly divided into five factions:albumin, α 1 -, α 2 -, β- and γ-globulins... The division into albumin and globulin was originally based on the difference in solubility: albumin are soluble in pure water, while globulins are only soluble in the presence of salts.

In quantitative terms, among plasma proteins, albumen(about 45 g / l), which plays an essential role in maintaining the colloidal osmotic pressure in the blood and serves as an important reserve of amino acids for the body. Albumin has the ability to bind lipophilic substances, so that it can function as a carrier protein for long-chain fatty acids, bilirubin, drugs, some steroid hormones and vitamins. In addition, albumin binds Ca 2+ and Mg 2+ ions.

The albumin fraction also includes transthyretin (prealbumin), which, together with thyroxine-binding globulin [TSGl (TBG)] and albumin, transports the hormone thyroxine and its metabolite iodothyronine.

The table lists other properties of important globulins blood plasma. These proteins are involved in the transport of lipids, hormones, vitamins and metal ions; they form important components of the blood coagulation system; the γ-globulin fraction contains antibodies of the immune system.

3. Hematopoiesis. Factors of erythropoiesis, leukopoiesis and thrombocytopoiesis. The concept of the blood system (G.F. Lang)

Hematopoiesis is the process of generating mature blood cells, of which the human body produces a little more than 400 billion per day. Hematopoietic cells are derived from a very small number of totipotent stem cells that differentiate into all blood cell lines. Totipotent stem cells are the least specialized. Pluripotent stem cells are more specialized. They are able to differentiate, producing only certain cell lines. There are two populations of pluripotent cells - lymphoid and myeloid.

Erythrocytes are derived from a pluripotent bone marrow stem cell that can differentiate into erythropoietic progenitor cells. These cells do not differ morphologically. Further, the progenitor cells differentiate into erythroblasts and normoblasts, the latter, in the process of division, lose their nucleus, accumulating hemoglobin more and more, reticulocytes and mature erythrocytes are formed, which enter the peripheral blood from the bone marrow. Iron binds to a circulating transport protein called transferrin, which binds to specific receptors on the surface of erythropoietic progenitor cells. The main part of iron is included in hemoglobin, the rest is reserved in the form of ferritin. After maturation, the erythrocyte enters the general bloodstream, its lifespan is approximately 120 days, then it is captured by macrophages and destroyed, mainly in the spleen. Heme iron is incorporated into ferritin and can also re-bind to transferrin and be delivered to bone marrow cells.

The most important factor in the regulation of erythropoiesis is erythropoietin, a glycoprotein with a molecular weight of 36,000. It is produced mainly in the kidneys under the influence of hypoxia. Erythropoietin controls the process of differentiation of progenitor cells into erythroblasts and stimulates the synthesis of hemoglobin. Other factors also affect erythropoiesis - catecholamines, steroid hormones, growth hormone, cyclic nucleotides. Essential factors for normal erythropoiesis are vitamin B12 and folic acid and sufficient iron.

Leukopoiesis(leucopoesis, leucopoiesis: leuko-+ Greek poiesis production, education; syn.: leukogenesis, leukocytopoiesis) - the process of formation of leukocytes

Thrombocytopoiesis(thrombocytopoesis; platelet + Greek poiēsis, production, formation) - the process of platelet formation.

Blood system - the concept was introduced by the Russian therapist Georgy Fedorovich Lang (1875-1948).

Denotes a system that includes peripheral blood, hematopoiesis and blood destruction organs, as well as the neurohumoral apparatus of their regulation.

4. Serrated and smooth tetanus. The concept of muscle tone. The concept of optimum and pessimum

Under natural conditions, not single impulses come to the skeletal muscle from the central nervous system, but a series of impulses following each other at certain intervals, to which the muscle responds with a prolonged contraction. Such a prolonged contraction of the muscle, which occurs in response to rhythmic stimulation, is called tetanic contraction or tetanus. There are two types of tetanus: serrated and smooth.

If each subsequent impulse of excitation arrives at the muscle during the period when it is in the shortening phase, then smooth tetanus appears, and if in the relaxation phase - dentate tetanus.

The amplitude of tetanic contraction exceeds the amplitude of a single muscle contraction. Proceeding from this, Helmholtz explained the process of tetanic contraction by a simple superposition, that is, by a simple summation of the amplitude of one muscle contraction with the amplitude of another. However, later it was shown that with tetanus, there is not a simple addition of two mechanical effects, since this sum can be either greater or less. N. Ye. Vvedensky explained this phenomenon from the point of view of the state of muscle excitability, introducing the concept of the optimum and pessimum of the frequency of stimulation.

Optimal is the frequency of stimulation at which each subsequent stimulation is carried out in the phase of increased excitability. In this case, tetanus will be maximum in amplitude - optimal.

Pessimal is the frequency of stimulation at which each subsequent stimulation is carried out in a phase of reduced excitability. In this case, tetanus will be minimal in amplitude - pessimal.

Tone
muscles - basic level
muscle activity, provided by its tonic contraction.

In normal
condition
at rest, all motor units of various muscles are in a well-organized complex background stochastic activity. Within one muscle in a given random
moment
time, some motor units are excited, others are at rest. At the next random moment in time, other motor units are activated. Thus, the activation of motor units is a stochastic function of two random variables - space and time. This activity of the motor units provides tonic muscle contraction, the tone of the given muscle and the tone of all muscles of the motor system. A certain mutual relation of the tone of different muscle groups ensures the posture of the body.

At the heart of the control of muscle tone and body posture at rest or during movement, the general strategy of control in living is of decisive importance.
systems - forecasting

5. Modern biophysical and physiological understanding of the mechanism of the appearance of membrane potential and excitation

Each cell at rest is characterized by the presence of a transmembrane potential difference (resting potential). Typically, the difference in charge between the inner and outer surfaces of membranes is -30 to -100 mV and can be measured using an intracellular microelectrode.

The creation of resting potential is provided by two main processes - the uneven distribution of inorganic ions between the intra- and extracellular spaces and the unequal permeability of the cell membrane for them. Analysis of the chemical composition of the extra- and intracellular fluid indicates an extremely uneven distribution of ions

Studies using microelectrodes have shown that the resting potential of a frog skeletal muscle cell ranges from -90 to -100 mV. Such a good agreement of the experimental data with the theoretical ones confirms that the rest potential is largely determined by the simple diffusion potentials of inorganic ions.

The active transport of sodium and potassium ions across the cell membrane is of great importance for the development and maintenance of the membrane potential. In this case, the transfer of ions occurs against the electrochemical gradient and is carried out with the expenditure of energy. Active transport of sodium and potassium ions is carried out by the Na + / K + - ATPase pump.

In some cells, active transport is directly involved in the formation of the resting potential. This is due to the fact that the sodium-potassium pump removes more sodium ions from the cell at the same time than brings potassium into the cell. This ratio is 3/2. Therefore, the potassium-sodium pump is called electrogenic, since it itself creates a small but constant current of positive charges from the cell, and therefore makes a direct contribution to the formation of a negative potential inside it.

The membrane potential is not a stable value, since there are many factors that affect the value of the resting potential of the cell: exposure to an irritant, changes in the ionic composition of the medium, exposure to certain toxins, disruption of tissue oxygen supply, etc. In all cases, when the membrane potential decreases, they speak of membrane depolarization, the opposite shift in the resting potential is called hyperpolarization.

Membrane theory of excitation is a theory that explains the emergence and propagation of excitation in the central nervous system by the phenomenon of semi-permeability of neuronal membranes, limiting the movement of ions of one type and passing ions of another type through ion channels.

6. Skeletal musculature as an example of pascellular structures - symplast

Skeletal muscles are part of the structure of the musculoskeletal system, are attached to the bones of the skeleton and, when contracted, set in motion individual links of the skeleton.

They participate in maintaining the position of the body and its parts in space, provide movement when walking, running, chewing, swallowing, breathing, etc., while generating heat. Skeletal muscles have the ability to be excited by nerve impulses. Excitation is carried out to the contractile structures (myofibrils), which, by contracting, perform a motor act - movement or tension.

There are about 600 muscles in humans, and most of them are paired. In each muscle, an active part (muscle body) and a passive part (tendon) are distinguished.

Muscles, the action of which is directed in the opposite direction, are called antagonists, unidirectionally - synergists. The same muscles in different situations can act in both capacities.

According to the functional purpose and direction of movement in the joints, flexor and extensor muscles, adductors and abductors, sphincters (compressing) and dilators are distinguished.

Simplast - (from the Greek syn - together and plastos - sculpted), a type of tissue in animals and plants, characterized by the absence of boundaries between cells and the location of nuclei in a continuous mass of cytoplasm. For example, striated muscles in animals, multinucleated protoplasts of some unicellular algae.

7. Regulation of the heart (intracellular, heterometric and homeometric). Starling's Law. Influence of the sympathetic and parasympathetic nervous systems on the activity of the heart

Although the heart itself generates impulses that cause its contraction, the activity of the heart is controlled by a number of regulatory mechanisms, which can be divided into two groups - extracardiac mechanisms (extracardiac), which include nervous and humoral regulation, and intracardiac mechanisms (intracardiac).

The first level of regulation is extracardiac (nervous and humoral). It includes the regulation of the main factors that determine the value of the minute volume, frequency and strength of heart contractions using the nervous system and humoral influences. Nervous and humoral regulation are closely related to each other and form a single neuro-humoral mechanism for regulating the work of the heart.

The second level is represented by intracardiac mechanisms, which, in turn, can be subdivided into mechanisms that regulate the work of the heart at the organ level, and intracellular mechanisms that predominantly regulate the strength of heart contractions, as well as the rate and degree of relaxation of the myocardium.

The central nervous system constantly monitors the work of the heart
through nerve impulses. Inside the cavities of the heart itself and in the walls of large vessels, there are nerve endings - receptors that perceive fluctuations in pressure in the heart and blood vessels. The impulses from the receptors cause reflexes that affect the work of the heart. There are two types of nervous influences on the heart: some are inhibitory,
that is, reducing the frequency of heart contractions, others - accelerating.

Impulses are transmitted to the heart through nerve fibers from nerve centers located in the medulla oblongata and spinal cord. Influences that weaken the work of the heart are transmitted along the parasympathetic nerves, and those that enhance its work - along the sympathetic.

For example, a person's heart contractions become more frequent when he quickly gets up from a lying position. The fact is that the transition to an upright position leads to the accumulation of blood in the lower part of the body and reduces the blood supply to the upper part, especially the brain. To restore blood flow in the upper torso, impulses are sent from the receptors of the vessels to the central nervous system.

From there, impulses are transmitted to the heart along nerve fibers that accelerate the contraction of the heart. These facts are a clear example of self-regulation of the heart.

Painful irritations also change the rhythm of the heart. Pain impulses enter the central nervous system and cause the heart to slow down or speed up. Muscular work always affects the activity of the heart. The inclusion of a large group of muscles in the work according to the laws of the reflex excites the center, which accelerates the activity of the heart. Emotions have a great influence on the heart. Under the influence of positive
emotions, people can do colossal work, lift weights, run long distances. Negative emotions, on the contrary, reduce the efficiency of the heart and can lead to disturbances in its activity.

Along with nervous control, the activity of the heart is regulated
chemicals constantly entering the bloodstream. This method of regulation through fluids is called humoral regulation.
A substance that inhibits the work of the heart is acetylcholine.

The sensitivity of the heart to this substance is so great that at a dose of 0.0000001 mg acetylcholine clearly slows down its rhythm. Another chemical, adrenaline, has the opposite effect. Adrenaline, even in very small doses, increases the work of the heart.

For example, pain causes the release of a few micrograms of adrenaline into the bloodstream, which markedly alters the activity of the heart. In medical practice, adrenaline is sometimes injected directly into the stopped heart to force it to contract again. Normal heart function depends on the amount of potassium and calcium salts in the blood. An increase in the content of potassium salts in the blood inhibits, and calcium enhances
the work of the heart. Thus, the work of the heart changes with changes in the conditions of the external environment and the state of the organism itself.

Starling's Law of the Heart, which shows the dependence of the force of heart contractions on the degree of myocardial distension. This law applies not only to the heart muscle as a whole, but also to an individual muscle fiber. The increase in the contraction force during stretching of the cardiomyocyte is due to the better interaction of the contractile proteins actin and myosin, and under these conditions the concentration of free intracellular calcium (the main regulator of the force of heart contractions at the cellular level) remains unchanged. In accordance with Starling's law, the strength of myocardial contraction is the greater, the more the heart muscle is stretched during the diastole period under the influence of the inflowing blood. This is one of the mechanisms that provide an increase in the force of heart contractions adequate to the need to pump into the arterial system exactly the amount of blood that flows to it from the veins.

8. Blood pressure in different parts of the vascular bed, method of registration and determination

Blood pressure is the hydrodynamic pressure of blood in the vessels, due to the work of the heart and the resistance of the walls of the vessels. Decreases with distance from the heart (the largest in the aorta, much lower in the capillaries, the smallest in the veins). Arterial pressure of 100-140 mm Hg (systolic) and 70-80 mm Hg (diastolic) is conventionally considered normal for an adult; venous - 60-100 mm water column. High blood pressure (hypertension) is a sign of hypertension, low blood pressure (hypotension) accompanies a number of diseases, but it is also possible in healthy people.

9. Types of cardiomyocytes. Morphological differences between contractile cells and conducting



	Slim and long	Elliptical	Thick and long
Length, micron	~ 60 ё140	~ 20	~ 150 ё200
Diameter, micron	~ 20	~ 5 d6	~ 35 ё40
Volume, μm 3	~ 15 ё45000	~ 500	135000 ё250000
The presence of transverse tubes	Many	Rare or absent	Absent
Presence of insert disks	Numerous end-to-end gap junctions of cells, providing a high speed of interaction.	Lateral cell connections or end-to-end connections.	Numerous end-to-end gap junctions of cells, providing a high speed of interaction.
General view of the muscle	A large number of mitochondria and sarcomeres.	The bundles of atrial muscle are separated by vast areas of collagen.	Fewer sarcomeres, less transverse striation

10. Carriage of gases by blood. Oxyhemoglobin dissociation curve. Features of the transport of carbon dioxide

Transport (transport) of respiratory gases, oxygen, O2 and carbon dioxide, CO2 with blood is the second of the three stages of respiration: 1. external respiration, 2. transport of gases by blood, 3. cellular respiration.

Final stages of respiration, tissue
respiration, biochemical oxidation are part of the metabolism. In the process of metabolism, end products are formed, the main of which is carbon dioxide. Condition
normal life activity is the timely removal of carbon dioxide from the body.

Mechanisms
carbon dioxide transport controls interact with regulatory mechanisms
acid-base balance of blood, regulation of the internal environment of the body as a whole.

11. Breathing in conditions of high and low atmospheric pressure. Decompression sickness. Mountain sickness

Decompression sickness - decompression sickness, which occurs mostly after caisson and diving operations in violation of the rules of decompression (gradual transition from high to normal atmospheric pressure). Signs: itching, joint and muscle pain, dizziness, speech disorders, confusion, paralysis. A therapeutic gateway is used.

Mountain sickness - develops in high altitude conditions due to a decrease in the partial stress of atmospheric gases, mainly oxygen. It can be acute (a type of altitude sickness) or chronically, with heart and lung failure and other symptoms.

12. Brief description of the walls of the airways. Types of bronchi, morphofunctional characteristics of small bronchi

Bronchi (from the Greek brónchos - windpipe, trachea), branches of the windpipe in higher vertebrates (amniotes) and humans. In most animals, the windpipe, or trachea, divides into two main bronchi. Only in the tuatara is the longitudinal groove in the posterior part of the windpipe marked by paired B., which do not have separate cavities. In other reptiles, as well as in birds and mammals, B. is well developed and continues inside the lungs. In reptiles, the main B. depart from B. of the second order, which can be divided into B. of the third, fourth order, etc .; the division of B. in turtles and crocodiles is especially difficult. In birds, B. of the second order are interconnected by parabronchs — channels from which so-called bronchioles branch off along the radii, branching out and passing into a network of air capillaries. Bronchioles and air capillaries of each parabronchus merge with the corresponding formations of other parabronchus, thus forming a system of through airways. Both the main B. and some lateral B. at the ends expand into the so-called air bags. In mammals, from each major B., there are secondary B., which are divided into ever smaller branches, forming the so-called bronchial tree. The smallest branches pass into the alveolar passages, ending in alveoli. In addition to the usual secondary B., in mammals there are pre-arterial secondary B. extending from the main B. in front of the place where the pulmonary arteries are thrown through them. More often there is only one right pre-arterial B., which in most artiodactyls departs directly from the trachea. The fibrous walls of large B. contain cartilaginous half rings, connected behind by transverse bundles of smooth muscles. B.'s mucous membrane is covered with ciliated epithelium. In small B., cartilaginous half rings are replaced by individual cartilaginous grains. There are no cartilage in the bronchioles, and the annular bundles of smooth muscles lie in a continuous layer. In most birds, the first B.'s rings are involved in the formation of the lower larynx.

In humans, the division of the trachea into 2 main B. occurs at the level of the 4-5th thoracic vertebrae. Each of B. then divides into smaller and smaller, ending in microscopically small bronchioles, passing into the alveoli of the lungs. B.'s walls are formed by hyaline cartilaginous rings, preventing B.'s collapse, and smooth muscles; inside B. are lined with a mucous membrane. In the course of B.'s ramifications, there are numerous lymph nodes that receive lymph from the tissues of the lung. B.'s blood supply is carried out by bronchial arteries extending from the thoracic aorta, innervation - by branches of the vagus, sympathetic, and spinal nerves.

13. Exchange of fats and its regulation

Fat is an important source of energy in the body, an essential component of cells. Excess fat can be deposited in the body. They are deposited mainly in the subcutaneous fatty tissue, omentum, liver and other internal organs. In the gastrointestinal tract, fat is broken down into glycerol and fatty acids, which are absorbed in the small intestine. Then it is synthesized again in the cells of the intestinal mucosa. The resulting fat is qualitatively different from the food fat and is specific to the human body. In the body, fats can also be synthesized from proteins and carbohydrates. Fats entering tissues from the intestines and from fat depots are oxidized through complex transformations, thus being a source of energy. When 1 g of fat is oxidized, 9.3 kcal of energy are released. As an energy material, fat is used in a state of rest and when performing prolonged low-intensity physical work. At the beginning of intense muscle activity, carbohydrates are oxidized. But after a while, due to a decrease in glycogen stores, fats and their breakdown products begin to oxidize. The process of replacing carbohydrates with fats can be so intense that 80% of all the energy required under these conditions is released as a result of fat breakdown. Fat is used as a plastic and energetic material, covers various organs, protecting them from mechanical stress. The accumulation of fat in the abdominal cavity ensures the fixation of the internal organs. Subcutaneous adipose tissue, being a poor conductor of heat, protects the body from excessive heat loss. Dietary fat contains some vital vitamins. The metabolism of fat and lipids in the body is complex. The liver plays an important role in these processes, where fatty acids are synthesized from carbohydrates and proteins. Lipid metabolism is closely related to the metabolism of proteins and carbohydrates. During fasting, fat stores serve as a source of carbohydrates. Regulation of fat metabolism. Lipid metabolism in the body is regulated by the central nervous system. If some nuclei of the hypothalamus are damaged, fat metabolism is disrupted and the body becomes obese or depleted.

14. Protein metabolism. Nitrogen balance. Positive and negative nitrogen balance. Regulation of protein metabolism

Proteins are essential building blocks of cell protoplasm. They perform special functions in the body. All enzymes, many hormones, visual purple of the retina, oxygen carriers, protective substances of the blood are protein bodies. Proteins are made up of protein elements - amino acids, which are formed during the digestion of animal and plant proteins and enter the bloodstream from the small intestine. Amino acids are divided into essential and non-essential. Indispensable are those that the body receives only with food. Replaceable ones can be synthesized in the body from other amino acids. The value of food proteins is determined by the amino acid content. That is why proteins from food are divided into two groups: complete, containing all essential amino acids, and defective, which lack some essential amino acids. Animal proteins are the main source of complete proteins. Vegetable proteins (with rare exceptions) are defective. In tissues and cells, the destruction and synthesis of protein structures is continuously going on. In a conditionally healthy body of an adult, the amount of decomposed protein is equal to the amount synthesized. Since the balance of protein in the body is of great practical importance, many methods have been developed for its study. Regulation of protein balance is carried out by humoral and nervous pathways (through hormones of the adrenal cortex and pituitary gland, diencephalon).

15. Heat transfer. Methods for transferring heat from a heat surface

The ability of the human body to maintain a constant temperature is due to complex biological and physicochemical processes of thermoregulation. In contrast to cold-blooded (poikilothermic) animals, the body temperature of warm-blooded (gamoyothermal) animals is maintained at a certain level when the temperature of the external environment fluctuates, which is most beneficial for the vital activity of the organism. The maintenance of the heat balance is carried out due to strict proportionality in the generation of heat and in its return. The amount of heat generation depends on the intensity of chemical reactions that characterize the level of metabolism. Heat transfer is mainly regulated by physical processes (heat radiation, heat conduction, evaporation).

The body temperature of humans and higher animals is maintained at a relatively constant level, despite fluctuations in the temperature of the external environment. This constancy of body temperature is called isotherm. Isothermia develops gradually during ontogenesis.

The constancy of body temperature in a person can be maintained only under the condition of equality of heat production and heat loss of the body. This is achieved through physiological thermoregulation, which is usually divided into chemical and physical. A person's ability to withstand the effects of heat and cold, while maintaining a stable body temperature, has certain limits. At an excessively low or very high temperature of the environment, the protective thermoregulatory mechanisms are insufficient, and the body temperature begins to drop or rise sharply. In the first case, a state of hypothermia develops, in the second, hyperthermia.

Heat generation in the body occurs mainly as a result of chemical metabolic reactions. Heat is generated during the oxidation of food components and other reactions of tissue metabolism. The amount of heat generation is closely related to the level of metabolic activity of the body. Therefore, heat production is also called chemical thermoregulation.

Chemical thermoregulation is especially important to maintain a constant body temperature under cooling conditions. When the ambient temperature decreases, the intensity of metabolism and, consequently, heat generation increase. In humans, an increase in heat production is noted in 1 case, when the ambient temperature becomes below the optimal temperature or comfort zone. In ordinary light clothing, this zone is in the range of 18-20 °, and for a naked person -28 ° C.

Total heat generation in the body occurs in the course of chemical metabolic reactions (oxidation, glycolysis), which is the so-called primary heat and when the energy of high-energy compounds (ATP) is expended to perform a slave (secondary heat). 60-70% of the energy is dissipated in the form of primary heat. The remaining 30-40%, after the breakdown of ATP, ensure the work of muscles, various processes of susecretion, etc. But even at the same time, one or another part of the energy is then transferred to heat. Thus, secondary heat is also formed as a result of exothermic chemical reactions, and when muscle fibers contract, as a result of their friction. Ultimately, either all the energy, or the overwhelming part of it, turns into heat.

The most intense heat generation in muscles during their contraction Relatively low motor activity leads to an increase in heat generation by 2 times, and hard work - 4-5 times or more. However, under these conditions, heat loss from the body surface increases significantly.

With prolonged cooling of the body, involuntary periodic contractions of the skeletal muscles occur. With this, almost all of the metabolic energy in the muscle is released as heat. Cold activation of the sympathetic nervous system stimulates lipolysis in adipose tissue. Free fatty acids are released into the bloodstream and subsequently oxidized with the formation of a large amount of heat. Finally, the importance of heat production is associated with an increase in the functions of the adrenal and thyroid glands. The hormones of these glands, increasing the metabolism, cause increased heat production. It should also be borne in mind that all physiological mechanisms that regulate oxidative processes affect at the same time the level of heat production.

The release of heat by the body is carried out by radiation and evaporation.

Radiation is lost about 50-55% went into the environment by radiation due to the infrared part of the spectrum. The amount of heat dissipated by the body (the environment with radiation is proportional to the surface area of the body parts that come into contact with the air and the difference in the average temperatures of the skin and the environment. The emission of radiation stops when the temperature of the skin and the environment is equalized).

Heat conduction can occur by conduction and evaporation. Heat is lost by conduction when parts of the human body are in direct contact with other physical environments. In this case, the amount of lost heat is proportional to the difference in the average temperatures of the contacting surfaces and the time of thermal contact. Convection is a method of heat transfer from the body, carried out by the transfer of heat by moving air particles.

Heat is dissipated by convection when air flows around the surface of the body with a lower temperature than the air temperature. The movement of air currents (wind, ventilation) increases the amount of heat released. Through heat conduction, the body loses 15-20% of the heat, while convection is a more extensive heat transfer mechanism than conduction.

Heat transfer by evaporation is a way of dissipation of heat (about 30%) by the body into the environment due to its costs for evaporation of sweat or moisture from the surface of the skin and mucous membranes of the respiratory tract. At an ambient temperature of 20 ″ moisture evaporation in humans is 600-800 g per day. When passing into 1 g of water, the body loses 0.58 kcal of heat. If the external temperature exceeds the average value of the skin temperature, then the body gives off heat to the external environment by radiation and conduction, and we are absorbed from the outside. Evaporation of liquid from the surface occurs when the air humidity is less than 100%.
Microscopic fungi as the main producers of various mycotoxins GENERAL CONCEPT OF THE STRUCTURE AND FUNCTIONS OF THE NERVOUS SYSTEM Functions of trade finance

2014-11-07

Which are characterized by the absence of color, the presence of a nucleus and the ability to move. The name is translated from Greek as "white cells". The group of leukocytes is heterogeneous. It includes several varieties that differ in origin, development, appearance, structure, size, core shape, and functions. Leukocytes are formed in the lymph nodes and bone marrow. Their main task is to protect the body from external and internal "enemies". There are leukocytes in the blood and in various organs and tissues: in the tonsils, in the intestines, in the spleen, in the liver, in the lungs, under the skin and mucous membranes. They can migrate to all parts of the body.

White cells are divided into two groups:

Granular leukocytes - granulocytes. They contain large nuclei of irregular shape, consisting of segments, which are the more, the older the granulocyte. This group includes neutrophils, basophils and eosinophils, which are distinguished by their perception of dyes. Granulocytes are polymorphonuclear leukocytes. ...
Non-granular - agranulocytes. These include lymphocytes and monocytes, which contain one simple oval nucleus and do not have a characteristic granularity.

Where are they formed and how long do they live?

Most of the white cells, namely granulocytes, are produced by the red bone marrow from stem cells. A progenitor cell is formed from the maternal (stem) cell, then passes into a leukopoietin-sensitive cell, which, under the action of a specific hormone, develops along the leukocyte (white) row: myeloblasts - promyelocytes - myelocytes - metamyelocytes (young forms) - stabs - segmented. Immature forms are located in the bone marrow, ripe ones enter the bloodstream. Granulocytes live for about 10 days.

In the lymph nodes, lymphocytes and a significant portion of monocytes are produced. Part of the agranulocytes from the lymphatic system enters the blood, which carries them to the organs. Lymphocytes live for a long time - from several days to several months and years. The lifespan of monocytes is from several hours to 2-4 days.

Structure

The structure of leukocytes of different types is different, and they look different. What everyone has in common is the presence of a core and the absence of their own color. The cytoplasm can be granular or homogeneous.